Coupler dispersions utilizing cyclohexane-containing esters as coupler solvents

ABSTRACT

A METHOD FOR INCORPORATING ONE OR MORE PHOTOGRAPHIC COLOR-FORMING COUPLERS INTO A COLOR PHOTOGRAPHIC ELEMENT OR CORRESPONDING EMULSION THEREOF UTILIZING AS COUPLER SOLVENT A LIQUID ESTER OF THE FORMULA   R-COO-(CH2)N-(CYCLOHEXYLENE)-(CH2)N-OOC-R   WHEREIN R IS INDIVIDUALLY DEFINED AT EACH OCCURENCE AS AN ALKYL GROUP HAVING 3-15 CARBON ATOMS; AND N IS INDIVIDUALLY DEFINED AT EACH OCCURRENCE AS 0-4.

United States Patent Int. Cl. G03c 1/40 U.S. Cl. 96100 36 Claims ABSTRACT OF THE DISCLOSURE A method for incorporating one or more photographic color-forming couplers into a color photographic element or corresponding emulsion thereof by utilizing as coupler solvent a liquid ester of the formula wherein R is individually defined at each occurrence as an alkyl group having 3-15 carbon atoms; and n is individually defined at each occurrence as O-4.

This invention relates to color photography and particularly to a method for efiiciently incorporating a substantially non-diffusible color coupler into a silver halide emulsion layer and to obtain a stable photographic dye by reacting the incorporated coupled with oxidized color developing agent.

Colo-r photographic processes in which coloring materials such as couplers are incorporated into a light-sensitive photographic layer are well known. Generally they involve the coupling of a color-forming compound with a primary aromatic amino developing agent to form a colored image.

In practical application the elementary color photographic element (its. the stored unexposed photographic element) comprises a support and a plurality of sensitized silver halide emulsion layers applied thereto; each emulsion layer, in turn, containing many dispersed droplets or particles consisting essentially of a coupler wholly or part- 1y dissolved in a high boiling water-insoluble coupler solvent or possibly encapsulated in a polymeric or wax-like material (French Pats. 2,017,718, 1,555,663 and U.S. Pat. 2,772,163).

In preparing dispersions of coupler compounds in silver halide emulsions it is customary to first dissolve the color former or coupler into the high boiling solvent, then disperse the coupler solution into an aqueous gelatin solution with a surfactant and mix the resulting dispersion with a light sensitive ge-latino-silver halide emulsion before coating onto a support. Ratios of coupler-to-solvent for this purpose customarily vary from about 1 to 2 or 1 to 3 (ref. examples Jelley and Vittum, U.S. Pat. 2,322,- 027), and a ratio of 1 to 1 can be used successfully with some couple-rs. The true solubility of most couplers in coupler solvents, however, is considerably lower than indicated by the above ratios. In many cases, the true solubility of the coupler does not exceed one part coupler in ten parts of coupler solvent. The dispersed coupler solution, therefore, is usually highly supersaturated.

Despite the above fact, the relatively large amount of inert coupler solvent required is considered disadvantageous because the solvent usually has no direct photographic function and also tends to decrease the durability of the emulsion layers.

For this reason, continuing efforts have been made to further cut down on the amount of solvent. For example, the use of certain high-boiling crystalloidal coupler solvents used alone or in combination with various removable auxiliary solvents have been helpful (ref. Julian U.S.

3,748,141 Patented July 24, 1973 Pat. 2,949,360; Mannes U.S. Pat. 2,304,939; Jelley et al. U.S. Pat. 2,322,827; Vittum U.S. Pat. 2,801,170; Fierke U.S. Pats. 2,801,171 and 2,490,749; Rinaura U.S. Pat. 3,554,755; Thirtle et a1. U.S. Pat. 2,835,579; Sawdey U.S. Pat. 2,533,514.

Such improved photographic emulsions are also generally summarized in Section XX'I'I, page 110, lines 1-50 of Product Licensing Index, vol. 92, publication 9232 (December 1971).

Because of marked differences in solubility among couplers and differences in coupler reactivity with oxidized developing agents, however, there is a continuing need for better coupler solvents and more efiicient techniques for utilizing couplers for general color photographic purposes.

It is an object of the present invention to improve the stability of coupler dispersion within photographic silver halide emulsions and to improve the heat stability of the photographic record obtained when such couplers react with oxidized color developing agents.

These and other objects are obtained 'by utilizing certain liquid esters of dihydric cycloalkanols as a high-boiling coupler solvent.

More specifically, the above objects can be obtained by the utilization of a liquid high-boiling coupler solvent of the formula wherein R is individually defined at each occurrence as an alkyl group having 3-15 carbon atoms, including straight or branched chain alkyl groups and preferably having 5-8 carbon atoms; and n is individually defined at each occurrence as 0-4 and preferably 1-4.

Hydrophobic liquid coupler solvents within the above class include the esters of a 1,4-dihydric cyclohexanol, a 1,3-dihydric cyclohexanol and the corresponding 1,3- and 1,4-hydroxy-lower alkylene derivatives exemplified in the following formulae R"o0-0--((3H,).u

toHom-o-oo-n" wherein R and R" are individually defined at each occurrence as an alkyl group as defined in Formula I above and n and m are individually defined as 0-2, preferably as l-2.

For purposes of the present invention, the term Permanent Coupler Solven is defined as a liquid cyclohexanecontaining ester of the type defined in Formulae I-III above which is retained in the coupler solvent droplets dispersed within the silver halide emulsion layer of the color photographic element.

The term Low-Boiling Auxiliary Solvent as used herein is intended to define low-boiling organic solvents having a water miscibility not exceeding about 6.5 parts/ parts of water and a boiling point range of about 76-205 C. Suitable auxiliary solvents of this type are listed, for instance, in Julian U.S. Patent 2,949,360.

Permanent coupler solvents within the present invention are more specifically described in the following table relative to Formulae II and HI.

TABLE I Permanent coupler solvent B. R" n 1n 1 CHa(CH:)4

2 CH:(CH:):CH 0

3 Same as above 1 4 5 CHa(CHz)aC|3H- 0 CgH 6 Same as above 1 .-...z: 7.- d0 4 8-... CHa(CH:)m- 0 l5 9- CHs(CH:)s 0

10.-;--..'.'. CH;(CH:):CH- 0 11 ame as above 1 12.- d0 4 13..'.-..'. CH;(CH:):(EH 0 14 Same as above 15 CH1(CHn)1r- 16 CHz-CH-(CH!) 17. Same as ab0ve-:.-...-.: n 4 18". CHg-CH-(CHz): 0

19...:.;.-:.:.:.:;:.:.;.:.:.;.:.:.;. ame as above.....'.;.:....-. 4

H 20 CH:- 0

H 21...';.'-.-.*. CHt( l)lt IHI TABLE II Permanent coupler solvent B R" n m 22 CHKCHflr- CH|(CH:)1(|3H- 0 23-.--:-'...'... CHs(CHg)4 24 CHs(CHz)4- 25 CH:(CH:)4

26"; CH3(CH3)|CH- 27 Sameasabove -.-...do 2 28 CH3(CHz)4 CHa(CH2)e 1 29 CH3(CH2)4 CH3(OH2)6' 1 Permanent solvents of the above-described type are conveniently obtained, for instance, in the manner described in US. Pat. 2,759,821 by reacting one molecular equivalent of quinitol (1,4-cyclohexanediol) and four molecular equivalents of 2-ethylhexoic acid at 205235 C. in the presence of zinc dust, while an azeotropic mixture of water and 2-ethylhexoic acid is distilled off. The desired product is then removed under reduced pressure. The portion boiling at 166l89 'C./ 0.3 mm. is collected as a. water-white liquid. (Coupler Solvent No. 5).

Another useful synthesis involves reacting 1,4 or 1,3 cyclohexane dialkanol with an excess of an alkanoic acid of from 6-13 carbon atoms in the presence of a platinum or zinc catalyst. The resulting product is then stripped under reduced pressure, neutralized with dilute sodium hydroxide solution, filtered, decanted, and the neutralized product dried and molecularly distilled to obtain the desired ester product.

Ballasted non-difiusible cyan dye-forming couplers suitable for use in the present invention are exemplified or suggested in U.S. Pats. 2,373,293; 2,423,730; 2,801,171; 2,895,826; 2,908,573; 3,046,129; 3,516,831; 3,311,476; 3,253,294; 3,458,315; 3,227,550; 3,476,563; 3,458,315; 3,419,390 and 3,034,892.

Useful non-ditfusible magenta dye-forming couplers are exemplified or suggested, for instance, in US. Pats. 2,600,788; 2,801,171; 2,983,608; 2,908,573; 3,252,924; 3,311,476; 3,227,550; 3,519,429; 3,432,521; 3,419,391; 3,227,554; 3,408,194; 3,214,437; 3,152,896; 3,062,653; 3,006,759 and Belgian Pat. 724,427.

correspondingly useful non-difi'usible yellow dyeforming couplers are exemplified or suggested in US. Pats. 2,778,658; 2,875,057; 2,908,573; 3,227,550; 3,253,924; 3,227,155; 3,408,194; 3,447,928; 3,415,652; 3,384,657; 3,369,895; 3,265,506; and 3,227,554.

For purposes of the present invention, it is also found that DIR (Development-Inhibitor-Releasing) couplers can also be usefully included in the silver halide emulsion layers within the present invention.

Compounds of this type are exemplified, for instance, in US. Pats. 3,227,554; 3,148,062 and US. Ser. 674,090, now US. Pat. No. 3,617,291, filed on Oct. 10, 1967.

An effective amount for non-ditfusible couplers of the above type can range from about 5-200 mg./ft. per emulsion layer of coated material, a concentration of 10-50 mg./ft. being generally satisfactory. Where DIR coupler is utilized in addition to 2- and/or 4-equivalent dye-forming couplers, it is found that about 5-30 mole percent of the former (i.e. DIR coupler) is adequate.

Color photographic elements within the scope of the present invention are preferably multilayered and usefully contain one or more of the following components:

(A) A support layer as described, for instance, in Section X of Product Licensing Index, vol. 92, publication 9232 (December, 1971). Typical supports include cellulose acetate film, polystyrene film, polyethylene film, polypropylene film, polylethylene terephthalate film, etc.

(B) Red-sensitive, a green-sensitive and a blue sensitive silver halide emulsion as summarized, for instance, on page 107 (Section I and III) and pages 108-9 (Section XV) of Product Licensing Index, vol. 92, publication 9232 (December 1971). Typical suitable silver halide emulsions include silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide, and silver chloroiodide emulsions.

Usefully included in such emulsion layers are the usual addenda including an antistain agent such as described in US. Pat. 2,865,752.

(C) One or more gelatin spacer layers can also be included between the light-sensitive emulsion layers and also a Carey-Lea filter layer; spacer layers of this type can optionally contain removable additives to further improve dye stability and improve color separation and (D) An ordinary protective gelatin overcoat layer.

The invention is further described although not limited by the following examples:

EXAMPLE I (A) A light-sensitive gelatino silver halide emulsion is prepared by dissolving 20 grams of 2-[u-(2,4-di-tert amylphenoxy)-acetamido]-4,6-dichloro 5 methylphenol (ref. US. Pat. 2,423,730) in 10 grams of di-n-butylphthalate in the presence of 30 ml. isopropylacetate as an auxiliary solvent. The resulting solution is poured into a mixture of 181 gm. of a 10% aqueous gelatin solution in the presence of an alkyl naphthylene sulfonate sodium salt as surfactant. The mixture is emulsified in a colloid The cyan image (neutral density 1.5) is then tested for.

heat stability in the usual manner at 77 C. (40% Relative Humidity) for one week and the density loss reported in Table III below.

(B) Example IA is repeated using quinitol di(2-ethyl hexoate (Permanent Solvent No. 5) as the high-boiling coupler solvent. The loss in density of the cyan record is reported in Table III as test strip T-2.

TABLE III Coupler] solvent Dens. Test strip Coupler solvent ratio loss T-l (control)-.- Di-n-butyl phthalate 1:% 5 T-2 Quinitol-di (2-ethyl hexoate) 1: A .28

(Solvent No. 5).

EXAMPLE II The tests reported in Example I and Table III are reported with three separate high-boiling coupler solvents used in varying ratio of coupler-to-solvent of 1:3, 1:2, 1:1 and 1: /2, and the test results reported in Table IV below.

TABLE IV Coupler] solvent Dens. Test strip Coupler solvent ratio loss T-3 (control)--- Di-n-butylphthalate 1:3 09 T4 (control) (lo 1:2 18 T-5 (control) ..do. 1:1 17 T-fi (control) do tVz 21 T-7 Quirfitol-di(2-ethylhexoate) 1:3 02

(Solvent No. 5). T-S 1:2 .05 T9 do..- 1:1 .10 T-lO ..do 1:56 .15 T-ll (control) Di-n-buty1phthalate 1:3 09 T-12 (control) do 1:% 36 T-13 1,d-cyclohexyldimethylenebis- 1:1 .10

j-cthylhexoate) (Solvent N o. T-l4 d0-.. 1:3 .02 T-li do- 1:1 .09 T-lfi do 1:}@ .14

EXAMPLE III (A) The experiment of Example I is repeated but with a multilayer color photographic print film comprising the following components:

(A) A cellulose acetate support layer;

(B) A blue-sensitive silver bromoiodide emulsion (1 mole percent I-) containing Ag (66 mg./dm. gelatin (36 mg./dm. and 3-[a-(2,4-di-t-amylphenoxy) butyramido]benzoyl}-2-methoxyacetanilide) (13.5 mg./ dm?) in di-n-butylphthalate (27 mg./dm.

(C) A gelatin interlayer (6.2 mg./dm.

(D) A red-sensitive silver chlorobromide emulsion (20 mole percent Br-) containing Ag (4.3 mg./dm. gelatin (31 mg./dm. and 2-(a-di-amylphenoxy-n-butyrylamino)-4,6-dichloro-5-methyl phenol (12.1 mg./dm. in di-n-butylphthalate (24.2 mg./dm.

(E) A gelatin interlayer (6.2 mg./dm.

(F) A green-sensitive silver chlorobromide emulsion (20 mole percent BF) containing Ag (8.6 mg./dm. gelatin (24 mg./dm. 1(2,4',6'-trichlorophenyl)-3-[3"- (2."',4' di-tert. amyl-phenoxyacetamido)benzamido]-5- pyrazolone (19 mg./dm. in di-n-butylphthalate (38 mg./dm. and

(G) A gelatin overcoat (9.8 mg./dm.

This film is exposed on an Eastman Model 1B sensitometer processed in the usual manner and tested for cyan dye stability at 77 C. (40% Relative Humidity) for 1 week and the density loss to red light is determined for a neutral image having a density of 1.5.

(B) A second test film is then prepared and tested which is identical with the film of Example IIIA with the exception that coupler Solvent No. 6 is substituted for di-n-butylphthalate in layer (D). The difierence in density loss between (A) and (B) elements is found to be substantially the same as that reported in Example I (Table I).

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. In a method for incorporating a photographic colorforming coupler in a hydrophilic colloid which comprises dissolving said coupler in an organic solvent and dispersing the resulting solution in said colloid; the improvement which comprises using as said organic solvent a solvent system containing a liquid ester of the formula wherein R is individually defined at each occurrence as an alkyl group having 3-15 carbon atoms; and n is individually defined at each occurrence as 0-4.

2. A method of claim 1 wherein the coupler is a phenolicor wnaphtholic-cyan dye-forming coupler compound.

3. In a method for incorporating a member selected from the group consisting of a phenolic cyan dye-forming coupler compound into a hydrophilic colloid, which comprises dissolving said coupler in an organic solvent and dispersing the resulting solution in said colloid, the improvement which comprises using as said organic solvent a solvent system containing (1) a liquid ester of the formulae wherein R' and R" are individually defined at each occurrence as an alkyl group of 5-8 carbon atoms; and n and m are individually defined as 0-2; and (2) a lowboiling auxiliary solvent.

4. A method of claim 3 wherein R and R" are branched alkyl groups of 5-8 carbon atoms and n and m are defined as 0-1.

5. The method of claim 3 wherein the auxiliary solvent is essentially water immiscible. 1

6. In a method for incorporating a photographic colorforming coupler in a hydrophilic colloid which comprises dissolving said coupler in an organic solvent and dispersing the resulting solution in said colloid; the improvement which comprises initially dissolving a phenolic cyan dyeforming coupler in a solvent system containing 1,4-cyclohexyl di rnethylene-bis(Z-ethylhexanoate) and a low-boiling auxiliary solvent having minimal miscibility in water.

7. In a method for incorporating a photographic colorforming coupler in a hydrophilic colloid which comprises dissolving said coupler in an organic solvent and dispersing the resulting solution in said colloid; the improvement which comprises initially dissolving a phenolic cyan dyeforming coupler in a solvent system containing quinitol di-(2-ethylhexoate) and a low-boiling auxiliary solvent having minimal miscibility in water.

7 8. A light-sensitive photographic silver halide emulsion having finely divided particles containing at least one color photographic coupler compound and a liquid substantially water-immiscible ester of the formula wherein R is individually defined at each occurrence as an alkyl group having 3-15 carbon atoms; and n is individually defined at each occurrence as -4.

9. A light-sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a phenolicor a-naphtholic-cyan dyeforming coupler compound and n is 1-4.

10. A light-sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is a S-pyrazolone or a l-H-pyrazolo [3,2-c]-s-triazole magenta dye-forming coupler compound; and n is 1-4.

11. A light-sensitive photographic silver halide emulsion of claim 8 wherein the color photographic coupler is an open-chain ketomethylene yellow dye-forming coupler compound; and n is 1-4.

12. A light-sensitive photographic silver halide emulsion containing finely divided particles comprising a member selected from the group consisting of a phenolic cyan dye-forming coupler compound and an a-naphtholic cyan dye-forming coupler compound; together with a liquid coupler solvent of the formulae wherein R and R are individually defined at each occurrence as an alkyl group of -8 carbon atoms; and n and m are individually defined as l-2.

13. A light-sensitive photographic silver halide emulsion containing finely divided particles comprising a member selected from the group consisting of a 5pyrazolone magenta dye-forming coupler, and a l-H-pyrazolo [3,2- c]s-triazole magenta dye-forming coupler compound, together with a liquid coupler solvent of the formulae (CH2)mOCOR" wherein R and R' are individually defined at each occurrence as an alkyl group of 5-8 carbon atoms; and n and m are individually defined as 1-2.

14. A light-sensitive photographic silver halide emulsion containing finely divided particles comprising a member selected from the group consisting of an acetoacetanilide yellow dye-forming coupler and a benzoylacetanilide yellow dye-forming coupler compound; together with a liquid coupler solvent of the formulae (CH2)mOCO-R" wherein R and R are individually defined at each occurrence as an alkyl group of 58 carbon atoms; and n and m are individually defined as l-2.

15. An emulsion of claim 12 wherein the coupler is a phenolicor ot-naphtholic-cyan dye-forming coupler; R

8 and R are branched alkyl groups of 5-8 carbon atoms and n and m are defined as l.

16. An emulsion of claim 13 wherein the coupler is a S-pyrazolone magenta dye-forming coupler; R and R are branched alkyl groups of 58 carbon atoms; and n and m are defined as l.

17. An emulsion of claim 14 wherein the coupler is an acetoacetanilide yellow dye-forming coupler in which the non-0x0 carbon atom of the aceto group is a tertiary carbon atom; R and R are branched alkyl groups of 58 carbon atoms; and n and m are defined as 1.

18. An emulsion of claim 9 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyl diethylenebis(2-ethylhexanoate).

19. An emulsion of claim 9 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexy1 diethylene-bis (Z-methylhexanoate) 20. An emulsion of claim 9 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyl dimethylene-bis Z-ethylhexanoate) 21. An emulsion of claim 9 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyl dimethylene-bis (Z-methylhexanoate 22. A color photographic element comprising a support layer and at least one light-sensitive silver halide emulsion layer having finely divided particles incorporated therein containing at least one color photographic dye producing coupler compound together with a coupler solvent of the formula wherein R is individually defined at each occurrence as an alkyl group having 3-15 carbon atoms; and n is individually defined at each occurrence as 0-4.

23. A color photographic element of claim 22 wherein the coupler is a phenolicor a-naphtholic-cyan dye-forming coupler; and n is 1-4.

24. A color photographic element of claim 22 wherein the coupler is a 5-pyrazoloneor a pyrazolo [3,2-c]-striazole-magenta dye-forming coupler; and n is 1-4.

25. A color photographic element of claim 22 wherein the coupler is an open-chain ketomethylene yellow dyeforming coupler; and n is 1-4.

26. A color photographic element comprising a support layer and at least one light-sensitive silver halide emulsion layer having finely divided particles incorporated therein containing at least one color photographic coupler compound and a liquid coupler solvent of the formulae wherein R and :R' are individually defined at each occurrence as an alkyl group of 58 carbon atoms; and n and m are individually defined as 1-2.

27. A color photographic element of claim 26 wherein the coupler compound is a phenolic cyan dye-forming coupler compound or an a-naphtholic cyan dye-forming coupler compound.

28. A color photographic element of claim 26 wherein the coupler compound is a 5-pyrazolone magenta dyeforming coupler or a 1 H pyrazolo [3,2-c1-s-triazole magenta dye-forming coupler compound.

29. A color photographic element of claim 26 wherein the coupler compound is an acetoacetanilideor a benzoylacetanilide-yellow dye-forming coupler compound.

30. A color photographic element of claim 26 wherein the coupler is a phenolic cyan dye-forming coupler; R and R" are individually defined as branched alkyl groups of 58 carbon atoms; and n and m are defined as 1.

31. A color photographic element of claim 26 wherein the coupler is a 5-pyrazolone magenta dye-forming coupler; R and R are individually defined as branched alkyl groups of 5-8 carbon atoms; and n and m are defined as 1.

32. A color photographic element of claim 26 wherein the coupler is an acetoacetanilide yellow dye-forming coupler in which the non-0x0 carbon atom of the aceto group is a tertiary carbon atom; R and R" are individually defined as branched alkyl groups of 5-8 carbon atoms; and n and m are defined as l.

33. A color photographic element of claim 23 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyldiethylene-bis- (Z-ethylhexanoate) 34. A color photographic element of claim 23 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyldiethylene-bis- (Z-methylhexano ate) l0 35. A color photographic element of claim 23 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexylene dimethyl-bis-(Z-ethylhexanoate) 36. A color photographic element of claim 23 wherein the liquid substantially water-immiscible ester is 1,4-cyclohexyldimethylene-bis (Z-methylhexanoate) References Cited UNITED STATES PATENTS 3,580,722 5/1971 Sakamoto et al. 96-100 NORMAN G. TORCHIN, Primary Examiner R. L. SCHILLING, Assistant Examiner U.S. Cl. X.R. 252-356, 364

$04050 UNITED STATES PATENT OFFICE g 69 CERTIFICATE OF CORRECTION Pam: No. 5, 34 Q bated uly 24, 1.973

. Albert c. Smith, Jr. Inventor(s) I It is certified that error appears in thejabove-identified patent I and that said Letters Patent are hereby corrected as shown below:

Column 1, line 28, "coupled" should read ---coupler--;

Column 3, line 26, "(CH should read (CH Column 3, line 40 (under'the heading *-0---- should I y be inserted; v

f o lumn 3, line 40 (under th e h eading "m") insert Column 6, line 45, insert between the twonformulas --or-- Column 8, line 54, Y in the formula "CC' should read CO---.

Signed" and sealed this 22nd day of January 1974 I (SEAL) Attest:

EDWARD M.FLETCHE R,JR. Q RENE D. TE GTMEY ER LAttesting Officer Acting Commissioner of Pate 

